Thread cutters or trimmers for sewing machines are well known in the art. In such cutters, the knives are frequently made of spring steel and/or are biased against one another under the influence of a spring. U.S. Pat. No. 4,332,209 to H. Gauch is one example of a thread trimming mechanism which employs a spring for biasing one blade against another. With either construction, the knives must press against each other such that the sliding pressure engagement therebetween is sufficient to operationally maintain a cutting relationship.
Although thread trimmers and cutters have been long known, diadvantages and drawbacks remain. The knives made of spring steel have a relatively high manufacturing cost because of their special shape and tolerances. As may be appreciated, those knives which are influenced into pressing engagement with each other by a spring require accurate calibration of the spring pressure. Too much pressure and the knife blade wear is intolerable. Too little pressure and the cutting relationship between the blades suffers. To accomplish and maintain the proper spring adjustment can be a timely, and thus costly process.